The present invention relates to the use of powerlines for transmission of high frequency signals. More particularly, but not exclusively, the present invention relates to the use of powerlines: in wireless communications where the powerlines are used as antenna; the communication of signals across transformers, open circuits or other devices associated with powerlines; and monitoring powerline noise to determine information about devices connected to a powerline. To assist in explanation of the present invention, problems associated with powerlines are discussed. Such problems may seem unrelated, without the benefit of this disclosure.
Generally, it is known to use powerlines for communications, such as may be used for home networking or other purposes. In such a network, computers or other network devices are interfaced to an outlet of the powerline and communications signals are sent over the power line. The powerline signals typically have a frequency of 60 Hz so a high pass filter can be used to filter out the 60 Hz. The communications signals sent over the power line are substantially higher such as on the order of 4 to 24 MHz. U.S. Pat. No. 6,243,413 to Beukema discloses one such example of using powerlines for communications. Various HomePlug® devices exist from multiple manufacturers. One problem exhibited by various examples of such devices is that such devices do not demonstrate adequate surge survivability. U.S. Pat. No. 6,130,896 to Luker et al. discloses another example of such a use of powerlines for communications. Luker et al. further discloses that a device connected to the powerlines may also be connected to an access point with an antenna for providing wireless communication.
Another problem related to communications over powerlines is the effect of open circuits, equipment such as transformers, or other devices or signals transmitted across the powerlines. Communications over powerlines may not be viable in certain applications unless effects of open circuits, equipment such as transformers, or other devices can be managed.
A seemingly unrelated problem is failure of devices connected to power lines, such as, but not limited to, transformers. Failure of such devices may result in disruptions of service. It would be advantageous if failure of such devices could be predicted prior to its occurrence so that devices could be repaired or replaced prior to failure.
Another seemingly unrelated problem relates to worker safety in large structures and mines. In the event of a disaster such as a structural failure or mine cave-in, locating workers as expeditiously as possible becomes a primary concern. Yet doing so can be difficult for a variety of reasons and presents a more complex set of problems than is present in other location finding applications. For example, services such as GPS are not options because the workers within certain structures, especially metal structures or workers who are underground have no line-of-sight to either GPS satellites or other workers. Radio signals become highly attenuated which makes it impractical to use conventional approaches. What is needed is a way to locate workers trapped within a large structure or in a mine.